[Scottish weather discussion - Spring 2023/24]

Cracking winter's day...a decent covering on the ground, some sunshine and frequent heavy snow showers. What's not to like? 

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

Just visiting to say good luck folks. I was lucky enough to be living in SW London during the Feb 2009 event - really magical and stands out as one of my favourite snow memories. If I recall correctly that 'sea effect' event was not modelled too well and the warnings only really came out as it started! Hopefully this one has been underplayed somewhat by the models. Early radar returns starting to shape up nicely... 

[Scotland Weather discussion]

Decent fall here. Haven't measured but looks like there is around 6 inches or so on the garden table. 

[Scotland Weather discussion]

Looks like a good 3-4 inches fallen overnight. Good start to the day - fingers crossed for more snow showers today and tomorrow. 

[Scotland Weather discussion]

First heavy snow of the winter. Settling on all surfaces just now...long may that continue.

[Scotland/Alba weather discussion - Jan 2021 onwards]

Heavy snow here for the last couple of hours. Almost whiteout conditions at times. Looks to be a good few inches additional cover so far. ..

[Scotland/Alba weather discussion - Jan 2021 onwards]

9 minutes ago, doctormog said:

It is showing up very nicely on the TrafficScotland road cameras currently. There seems to be some form of intermittent sleet here this evening.

Fingers crossed as the night goes on and the colder air digs in we'll see more and more parts of the city come into the game. 

 

11 minutes ago, Wee County Exile said:

Where is highest point in the city ? Must be in Mastrick ?

Turning to snow in culter now - lower uppers must be kicking in now ? 

 

Excluding western suburbs I would presume so. Good to see more snow being reported in the region!

[Scotland/Alba weather discussion - Jan 2021 onwards]

11 minutes ago, Zerouali lives said:

Where in Aberdeen are you at 156m? Highest point in the city is 130m so you must be just outside somewhere...

Kingswells - still technically a city suburb but right on the city/shire border. Snow getting heavier now and building nicely.

[Scotland/Alba weather discussion - Jan 2021 onwards]

17 minutes ago, Zerouali lives said:

Just  been for a walk in the higher parts of Aberdeen between 110 - 130m - snow falling is dry and is lying on some cars and grassy verges. otherwise just a very thin layer of slush which should turn white overnight.

Nothing but sleet and wetness at 33m

Can confirm a good covering on all surfaces here. Hopefully it stays that way...

[Cold hunt - models and chat]

Good trend from the GFS within the 120-144hr time period...perilously close to unleashing the beast. If we can squeeze a wedge of high pressure between GL and Scandi the link-up would surely be in the offering. UKMO not so good but room for improvement. As long as that Siberian high lurks in the NE we will always be in with a shout. One to watch over the coming days.

[Cold hunt - models and chat]

34 minutes ago, TEITS said:

Indeed mate. Remember back in Feb 2005 when at one stage the models were predicting the dreaded Euro HP which actually reversed into a whooping Greenland HP.

Normally we always expect downgrades when it comes to cold spells but sometimes the reverse happens and as you say there is no meterological reason why this cannot happen. I can see why the Met O have continued with their extended outlook.

Yes and I can't see the Met changing their outlook either as there are no strong signals for anything just yet. I know certain folk look for trends in the ens but that has proven useless time and time again.

The movement of the Siberian high is notoriously difficult to predict, particularly on the northern fringes around the Kara strait locale. Historically, if we can get pressure to build into that territory it is a precursor to a cold shot into Europe. If there is more support for pressure building around Kara and into Svalbard in the next few runs things could get very interesting indeed. Let's not forget the Kettley high saga back in Feb 2001!  

[Cold hunt - models and chat]

Hopefully the GFS is picking up on a trend for that ridge being thrown up to Scandi...interesting...and ties in with the Met outlook.

[Cold hunt - models and chat]

As has been noted, ECM op looks a bit of an outlier so don't think we should be reading too much into that run. Looking across all models, the picture isn't as bad as some are making out. Plenty of interest being shown on GEFS, GEM ens and a couple of the lesser models. Don't take any run in isolation, particularly given the highly turbulent background. 

[Cold hunt - models and chat]

The ECM more or less follows the mean up to day 7 and the envelope is pretty tight. Thereafter, there is some divergence as expected, although that is well outside any semi reliable time frame. It's worth remembering how useless the ensembles have been so far this winter, so probably wise not to go looking for any trends beyond 120hrs as they are likely meaningless. 

[Stratosphere and Polar Vortex Watch]

Knowing our luck there will be an instant downwelling of the w'lys that negates the e'lys! Seriously, given the lagged response and the fact that the PV will be weakening at the back end of winter anyhow, I'm led to believe its influence would be minimal. Let's hope we have some HLB in place prior to that though. 

[Cold hunt - models and chat]

An improved 06z but still not liking that quasi stationary PV chunk sat over NE Canada. Even if we get the ridge up into GL there is potential it could be flattened quite quickly resulting in a transitory spell of colder air. If that chunk doesn't migrate south or west we could really do with some blocking assistance from the NE.  

[Scotland/Alba Weather Discussion 2019]

First snow of the winter here and about time! It's not much (probably an inch), but its a start.

[Meto Uk Further Outlook]

2 minutes ago, feb1991blizzard said:

its flipped, not necessarily to a mild outlook - but to a more average one.

How do we know it's flipped? Not sure that tweet the other day was from a reliable source...

[Meto Uk Further Outlook]

Given the uncertainty, the MO are just covering all bases. They have always maintained that milder air may make inroads to parts of the south - usually indicative of waves of low pressure moving along the channel. This is a good thing if you want frontal snow... 

[Model output discussion - 7th January onwards]

The UKMO hasn't changed that much since its run yesterday pm and its difficult to see where that will lead as the key period is post 144hr. The ECM certainly isn't without support - look at the GEM op and many of it's ensemble members as well as the JMA. The ECM mean is also rock solid. You'd have to assume the higher resolution models have a better handle on this and you'd be a brave person to bet against the ECM suite. 

[Stratosphere and Polar Vortex Watch]

7 minutes ago, bradythemole said:

You can see from this particular graphic on the MetOffice video that negative zonal winds propagate down to troposphere from I would say 20th or Jan or so gauging from the graph and stay negative for rest of winter even though positive winds return at the top. 

wonder if this is GloSea data?

 

Must be from GloSea as that is the only model that runs that far out. As you say, it is the duration of negativity that is an eye opener. Could be a modelling error but I wonder if previous SSWs had such a lasting impact. Back loaded winter looks odds on based on current data.

[Model output discussion - 7th January onwards]

5 minutes ago, Mike Poole said:

Outrageous run, FV3 at T360:

Dangerous cold over NE America. -30C 850hPa isotherm almost touching NYC!

[Stratosphere and Polar Vortex Watch]

1 hour ago, Redbull165 said:

On ECMWF model we can see the downward propagation is still lagging in the area below the 100 hPa in the troposfere. This SSW event is really slow with its effect. But I hope it will be worth the wait.

I'm curious to see how well that matches with reality in 10 days time. If that forecast is to be believed it explains why there would be nothing of interest being shown in the models until well beyond 17th. Hopefully the models are underplaying the rate of downwelling.

If someone has a link to view these charts as observed on a daily basis since the split that would be most interesting. Also curious to monitor if there will be moderation of the negative values as it propagates down into the troposphere.  

[The Hunt for Cold continues 02/01/19]

The run has finished but seems stuck on Meteociel. The old fashioned way still works:

 http://www.wetterzentrale.de/en/topkarten.php?map=2&model=gfs&var=1&run=6&time=384&lid=OP&h=0&mv=0&tr=3#mapref

The high eventually collapses into Europe but pressure build to the NE looks likely thereafter. 

[Stratosphere and Polar Vortex Watch]

6 minutes ago, snowking said:

I don’t have the time for a full reply right now - and we should still be cautious of any model output at such a range without some ensemble consensus (which fortunately we do have to a large extent at the moment). But the primary reason that stratospheric modelling should in theory be more accurate is that it is an easier environment to model - you don’t have large geographic features like bodies of water and big mountains in the way, you’re essentially dealing with a flat “surface”. Of course, there is always the argument that as tropospheric behaviour can affect the stratosphere, it is still open to the same flaws, but generally the physics of the situation should be easier to handle

Yup completely agree with the environment being easier to model as less variables etc but I was specifically referring to forecasting SSW events - the initiator for these comes from the troposphere so surely usual limitations apply.